The present invention is generally directed to toner processes, and more specifically to aggregation and coalescence processes for the preparation of toner compositions. In embodiments, the present invention is directed to the economical preparation of toners without utilization of the known pulverization and/or classification methods, and wherein toner compositions with an average volume diameter of from about 1 to about 25, and preferably from 1 to about 10 and more preferably from about 3 to about 7 microns in average volume, and narrow GSD of, for example, from about 1.16 to about 1.26 as measured on the Coulter Counter, can be obtained. The resulting toners can be selected for known electrophotographic imaging and printing processes, including color processes, and lithography. In embodiments, the present invention is directed to a process comprised of dispersing a pigment and optionally a charge control agent or additive in an aqueous mixture containing an ionic surfactant in amount of from about 0.01 percent (weight percent throughout unless otherwise indicated) to about 10 percent and shearing this mixture at high speeds, for example, in the range of about 3,000 to about 15,000 rpm (revolutions per minute) and preferably in the range of about 6,000 to about 12,000 rpm with a latex mixture comprised of suspended resin particles of from, for example, about 0.01 micron to about 1 micron in volume average diameter, in an aqueous solution containing a counterionic surfactant in amounts of from about 0.01 percent to about 10 percent with opposite charge to the ionic surfactant of the pigment dispersion, and nonionic surfactant in amount of from 0 percent to about 5 percent, thereby causing a flocculation of resin particles, pigment particles and optional charge control particles, followed by heating about 5.degree. C. to about 35.degree. C. and preferably about 5.degree. C. to about 20.degree. C. below the resin Tg, which range is generally between about 40.degree. C. to about 80.degree. C. and preferably in the range of about 50.degree. C. to about 75.degree. C. to form statically bound aggregates of from about 1 micron to about 10 microns in volume average diameter comprised of resin, pigment and optional charge control components. The flocculation or the heterocoagulation of the pigment particles containing ionic surfactant in amounts of about 0.01 percent to 10 percent and preferably between 0.1 percent to 5 percent with the latex mixture comprised of submicron resin particles containing the counterionic surfactant in the amounts of 0.01 percent to 10 percent and preferably between 0.1 percent to 5 percent causes a significant increase in the viscosity of the system, an increase, for example, of from about 4 centipoise to about 3,000 centipoise, resulting in big clusters or flocculants. Without the breakdown of these clusters or flocculants, a noncontrolled aggregation in step (iii) can be obtained in embodiments resulting in particle size and GSD of unacceptable or undesirable values. By applying a high shear of, for example, about 3,000 to about 15,000 rpm and preferably between about 5,000 and 12,000 rpm at the step (ii) stage, a homogeneous or a uniform blend is obtained whereby the big clusters or flocculants are broken or reduced to about submicron size, for example about 0.05 to about 1 micron, followed by heating to from about 40.degree. C. to about 5.degree. C. and preferably about 25.degree. C. to about 5.degree. C. below the resin Tg, which is generally in the range of about 40.degree. C. to about 80.degree. C. and preferably between about 50.degree. C. to about 75.degree. C. to form the statically bonded aggregates of step (iii). The aforementioned increase in viscosity, an increase of, for example, from about 2 centipoise to about 2,000 centipoise is primarily a result of the combination of pigment particles containing ionic surfactant with the latex mixture comprised of submicron resin particles containing the counterionic surfactant coming together (charge neutralization), and also a function of the solids of resin, pigment and optional charge control additives, or volume fraction loading in step (ii), for example at 20 percent loading the viscosity can be as high as 10,000 centipoise. The zeta potential of the latex prepared by emulsion polymerization containing resin in the anionic/nonionic surfactant can also be another factor, for example a latex measured zeta potential of about -100 millivolts can require a larger quantity of the counterionic surfactant to that of the said ionic surfactant in the latex for charge neutralization and hence flocculation to occur. Also, the amounts of the ionic to counterionic surfactants employed independent of the solids loading or the zeta potential of the latex can lead to an increase of viscosity, for example with a 2:1 molar ratio of cationic to anionic surfactant increases the viscosity of the blend increases to from about 2 to about 3,000 centipoise. These and other factors, especially the solids loading, the high zeta potential of the latex, and the molar ratios of the ionic to counterionic surfactant can result in an increase in viscosity, for example from about 2,000 to about 8,000 centipoise. High shear devices, such as a polytron, a homogenizer, a continuous IKA shearing device or a Dispax-reactor and the like thereof, are substantially unable to effectively process high viscosity mixtures and break down the huge clusters or flocculants formed. Therefore, the viscosity can increase to such an extent that the shearing power of the aforementioned equipment is rendered uneffective as it is not able to break down the huge clusters, resulting in an uncontrolled aggregation (step iii) and providing unacceptable particle size distribution, GSD, in the range of 1.85 to 3.5.
In another embodiment thereof, the present invention is directed to an in situ process comprised of first dispersing a pigment, such as HELIOGEN BLUE.TM. or HOSTAPERM PINK.TM., in an aqueous mixture containing a cationic surfactant, such as benzalkonium chloride (SANIZOL B-50.TM.), utilizing a high shearing device, such as a Brinkmann Polytron, microfluidizer or sonicator, thereafter shearing at high speeds in the range of 30,00 to 15,000 rpm and preferably between 5,000 and 12,000 rpm this mixture with a latex of suspended resin particles, such as poly(styrene butadiene acrylic acid), poly(styrene butyl acrylate acrylic acid) or PLIOTONE.TM., a poly(styrene butadiene), and which particles are, for example, of a size ranging from about 0.01 to about 0.5 micron in volume average diameter as measured by the Brookhaven nanosizer in an aqueous surfactant mixture containing an anionic surfactant, such as sodium dodecylbenzene sulfonate (for example NEOGEN R.TM. or NEOGEN SC.TM.) and nonionic surfactant, such as alkyl phenoxy poly(ethylenoxy) ethanol (for example IGEPAL 897.TM. or ANTAROX 897.TM.), thereby resulting in a flocculation, or heterocoagulation of the resin particles with the pigment particles; and wherein the resulting flocculated mixture is pumped through the shearing chamber, or zone at very high speeds generally in the range of 3,000 to 15,000 and preferably between 5,000 to 12,000 rpm, and is continuously recirculated for about 1 to about 120 minutes while being stirred at 200 rpm in a holding tank. This shearing can generally consume from about 1 minute to about 120 minutes to achieve a homogeneous or a uniform blend with a consistency of whip cream as contrasted to a cottage cheese consistency. The blend comprises very small, submicron in size, clusters of resins, and optional charge control agents, which are then allowed to grow by heating the mixture from about 5.degree. C. to about 25.degree. C. below the resin Tg, which resin Tg is preferably equal to 54.degree. C. and generally is in the range of about 40.degree. C. to about 80.degree. C. and preferably in the range of about 50.degree. C. to about 75.degree. C., and increase the speed, up to 10 times quicker, of the growth of the aggregates in a controlled manner while stirring at a speed of about 300 to about 800 rpm. This results in the formation of statically bound aggregates ranging in size of from about 0.5 micron to about 10 microns in average volume diameter size as measured by the Coulter Counter (Multisizer II). Extra anionic or nonionic surfactant, in an amount of about 0.5 to 5 percent by weight of water, can be added to the mixture to stabilize the aggregates formed. Thereafter, heating from about 5.degree. C. to about 50.degree. C. above the resin Tg, which resin Tg is in range of from about 50.degree. C. to about 75.degree. C. is accomplished to provide for particle fusion or coalescence of the polymer, or resin and pigment particles; followed by washing with, for example, hot water to, for example, remove surfactants; and drying whereby toner particles comprised of resin and pigment with various particle size diameters can be obtained, such as from 1 to 12 microns in average volume particle diameter. The aforementioned toners are especially useful for the development of colored images with excellent line and solid resolution, and wherein substantially no background deposits are present. While not being desired to be limited by theory, it is believed that the flocculation or heterocoagulation is caused by the neutralization of the pigment mixture containing the pigment and cationic surfactant absorbed on the pigment surface, with the resin mixture containing the resin particles, and anionic surfactant absorbed on the resin particle. This can be considered a kinetically controlled process. Furthermore, in other embodiments the ionic surfactants can be exchanged, such that the pigment mixture contains pigment and anionic surfactant, and the suspended resin mixture contains the resin particles and cationic surfactant; followed by the ensuing steps as illustrated herein to enable flocculation by charge neutralization while shearing at high speed, generally in the range of about 3,000 to about 15,000 rpm and preferably in the range of 3,000 to 12,000 rpm, to ensure a uniform or a homogeneous mixture comprising small, submicron to 1 micron size, clusters or flocks, and thereby forming statically bounded or attached aggregate particles by stirring and heating at about 5.degree. C. to about 25.degree. C. below the resin Tg, which resin Tg is in the range of about 40.degree. C. to about 80.degree. C. and preferably between 50.degree. C. and 75.degree. C., and thereafter, heating the statically bound aggregates from about 5.degree. C. to about 50.degree. C. above the resin Tg at temperatures of from about 60.degree. C. to about 100.degree. C. to form stable toner compositions. Of importance with respect to the processes of the present invention in embodiments is the utilization of high speed shearing devices, such as rotator(s)-stator(s), for example polytrons, homogenizers, megatrons, disintegrators, high efficiency dispensers, and the like in step (ii) as illustrated herein to achieve a narrow particle size distribution which generally is in the range of 1.18 to 1.27 upon aggregating (step iii) the particles by stirring from about 200 to about 800 rpm, and heating at about 5.degree. C. to about 25.degree. C. below the resin Tg which is in the range of about 40.degree. C. to about 80.degree. C. and preferably between 50.degree. C. to 75.degree. C.; (iv) adding extra anionic surfactant or nonionic surfactant from about 0.5 to about 5 weight percent of water to stabilize the aggregates of (iii), heating about 5.degree. C. to about 50.degree. C. above the resin Tg (step v) to form stable toner composite particles comprising resin, pigment particles, and optional charge control agent. Without the use of the aforementioned high speed devices, the particle size distribution (GSD) obtained can be very broad, for example using helical or turbine blades and the like the GSD obtained is generally in the range of 1.80 to 3.22. Although the speed of the agitator can be high, for example 650 rpm using a 10.5 centimeters in length.times.3.0 centimeters high turbine blade in a kettle size of 13 centimeters diameter by 17 centimeters high and containing about 900 grams of mixture having a viscosity of about 1,300 centipoise, insufficent shear force is present to effectively break down the large clusters or the mass flocculants of resin and pigment particles resulting in none or very little size reduction. Generally, these ordinary types of agitators create very little shear force and hence their application in step (ii) can lead to undesired particle size and broad GSD upon aggregating the step (iii) components.
In reprographic technologies, such as xerographic and ionographic devices, toners with average volume diameter particle sizes of from about 9 microns to about 20 microns are effectively utilized. Moreover, in some xerographic technologies, such as the high volume Xerox Corporation 5090 copier-duplicator, high resolution characteristics and low image noise are highly desired, and can be attained utilizing the small sized toners of the present invention with, for example, an average volume particle size of 2 to 11 microns and preferably less than about 7 microns, and with narrow geometric size distribution (GSD) of from about 1.16 to about 1.3. Additionally, in some xerographic systems wherein process color is utilized, such as pictorial color applications, small particle size colored toners of from about 3 to about 9 microns are highly desired to avoid paper curling. Paper curling is especially observed in pictorial or process color applications wherein three to four layers of toners are transferred and fused onto paper. During the fusing step, moisture is driven off from the paper due to the high fusing temperatures of from about 130.degree. C. to about 160.degree. C. applied to the paper from the fuser. Where only one layer of toner is present, such as in black or in highlight xerographic applications, the amount of moisture driven off during fusing is reabsorbed proportionally by paper and the resulting print remains relatively flat with minimal curl. In pictorial color process applications wherein three to four colored toner layers are present, a thicker toner plastic level present after the fusing step inhibits the paper from sufficiently absorbing the moisture lost during the fusing step, and image paper curling results. These and other disadvantages and problems are avoided or minimized with the toners and processes of the present invention. It is preferable to use small toner particle sizes, such as from about 1 to 7 microns and with higher pigment loading such as from about 5 to about 12 percent by weight of toner, such that the mass of toner layers deposited onto paper is reduced to obtain the same quality of image and resulting in a thinner plastic toner layer onto paper after fusing, thereby minimizing or avoiding paper curling. Toners prepared in accordance with the present invention enable the use of lower fusing temperatures, such as from about 120.degree. C. to about 150.degree. C., thereby avoiding or minimizing paper curl. Lower fusing temperatures minimize the loss of moisture from paper, thereby reducing or eliminating paper curl. Furthermore, in process color and especially in pictorial color, toner to paper gloss matching is highly desirable. Gloss matching is referred to as matching the gloss of the toner image to the gloss of the paper. For example, when a low gloss image of preferably from about 1 to about 30 gloss is desired, low gloss paper is utilized, such as from about 1 to about 30 gloss units as measured by the Gardner Gloss metering unit, and which after image formation with small particle size toners of from about 3 to about 5 microns and fixing thereafter results in a low gloss toner image of from about 1 to about 30 gloss units as measured by the Gardner Gloss metering unit. Alternatively, if higher image gloss is desired, such as from about above 30 to about 60 gloss units as measured by the Gardner Gloss metering unit, higher gloss paper is utilized, such as from about above 30 to about 60 gloss units, and which after image formation with small particle size toners of the present invention of from about 3 to about 5 microns and fixing thereafter results in a higher gloss toner image of from about 30 to about 60 gloss units as measured by the Gardner Gloss metering unit. The aforementioned toner to paper matching can be attained with small particle size toners such as less than 7 microns and preferably less than 5 microns, such as from about 1 to about 4 microns such that the pile height of the toner layer(s) is considered low.
Numerous processes are known for the preparation of toners, such as, for example, conventional processes wherein a resin is melt kneaded or extruded with a pigment, micronized and pulverized to provide toner particles with an average volume particle diameter of from about 9 microns to about 20 microns and with broad geometric size distribution of from about 1.4 to about 1.7. In these processes, it is usually necessary to subject the aforementioned toners to a classification procedure to obtain a toner geometric size distribution of from about 1.2 to about 1.4. Also, in the aforementioned conventional process, low toner yields after classifications may be obtained. Generally, during the preparation of toner with average particle size diameters of from about 11 microns to about 15 microns, toner yields range from about 70 percent to about 85 percent after classification. Additionally, during the preparation of smaller sized toners with particle sizes of from about 7 microns to about 11 microns, lower toner yields are obtained after classification, such as from about 50 percent to about 70 percent. With the processes of the present invention in embodiments, small average particle sizes of, for example, from about 3 microns to about 9, and preferably 5 microns are attained without resorting to classification processes, and wherein narrow geometric size distributions are obtained, such as from about 1.16 to about 1.30, and preferably from about 1.16 to about 1.25. High toner yields are also attained, such as from about 90 percent to about 98 percent, in embodiments. In addition, by the toner particle preparation process of the present invention in embodiments, small particle size toners of from about 3 microns to about 7 microns can be economically prepared in high yields such as from about 90 percent to about 98 percent by weight based on the weight of all the toner material ingredients, such as toner resin and pigment.
There is illustrated in U.S. Pat. No. 4,996,127 a toner of associated particles of secondary particles comprising primary particles of a polymer having acidic or basic polar groups and a coloring agent. The polymers selected for the toners of the '127 patent can be prepared by an emulsion polymerization method, see for example columns 4 and 5 of this patent. In column 7 of this '127 patent, it is indicated that the toner can be prepared by mixing the required amount of coloring agent and optional charge additive with an emulsion of the polymer having an acidic or basic polar group obtained by emulsion polymerization. Also, note column 9, lines 50 to 55, wherein a polar monomer, such as acrylic acid, in the emulsion resin is necessary, and toner preparation is not obtained without the use, for example, of acrylic acid polar group. The process of the present invention need not utilize polymer polar acid groups, and toners can be prepared with resins such as poly(styrene-butadiene) or PLIOTONE.TM. containing no polar acid groups. Additionally, the process of the '127 patent does not appear to utilize counterionic surfactant and flocculation process as does the present invention, and does not use a counterionic surfactant for dispersing the pigment. In U.S. Pat. No. 4,983,488, there is illustrated a process for the preparation of toner by the polymerization of a polymerizable monomer dispersed by emulsification in the presence of a colorant and/or a magnetic powder to prepare a principal resin component and then effecting coagulation of the resulting polymerization liquid in such a manner that the particles in the liquid after coagulation have diameters suitable for a toner. It is indicated in column 9 of this patent that coagulated particles of 1 to 100, and particularly 3 to 70, are obtained. This process is thus directed to the use of coagulants, such as inorganic magnesium sulfate which results in the formation of particles with wide GSD. Furthermore, the '488 patent does not disclose the process of counterionic, for example obtaining controlled aggregation by changing the counterionic strength, flocculation as the present invention. The aforementioned disadvantages of, for example, poor GSD are obtained, hence classification is required resulting in low yields, are illustrated in other prior art, such as U.S. Pat. No. 4,797,339, wherein there is disclosed a process for the preparation of toner by resin emulsion polymerization, wherein similar to the '127 patent polar resins of opposite charges are selected, and wherein flocculation as in the present invention is not disclosed; and U.S. Pat. No. 4,558,108, wherein there is disclosed a process for the preparation of a copolymer of styrene and butadiene by specific suspension polymerization. Other prior art that may be of interest includes U.S. Pat. Nos. 3,674,736; 4,137,188 and 5,066,560.
The process described in the present application has several advantages as indicated herein including the effective preparation of small toner particles with narrow particle size distribution; yields of toner are high; large amounts of power consumption are avoided; the process can be completed in rapid times, therefore, rendering it attractive and economical; and it is a controllable process since the particle size of the toner can be tightly controlled by, for example, controlling the temperature of the aggregation, and the desired particle size distribution can be obtained by controlling the shear, speed and time of the blending.
In U.S. Pat. No. 5,290,654 (D/92277), the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toners comprised of dispersing a polymer solution comprised of an organic solvent, and a polyester and homogenizing and heating the mixture to remove the solvent and thereby form toner composites. Additionally, there is disclosed in U.S. Pat. No. 5,278,020 (D/92097), the disclosure of which is totally incorporated herein by reference, a process for the preparation of in situ toners comprising an halogenization procedure which, for example, chlorinates the outer surface of the toner and results in enhanced blocking properties. More specifically, this patent application discloses an aggregation process wherein a pigment mixture containing an ionic surfactant is added to a resin mixture containing polymer resin particles of less than 1 micron, nonionic and counterionic surfactant, thereby causing a flocculation which is dispersed to statically bound aggregates of about 0.5 to about 5 microns in volume diameter as measured by the Coulter Counter, and thereafter heating to form toner composites or toner compositions of from about 3 to about 7 microns in volume diameter, and which exhibit, for example, low fixing temperature of from about 125.degree. C. to about 150.degree. C., low paper curling, and image to paper gloss matching.
In U.S. Pat No. 5,308,734 (D/92576), the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner compositions which comprises generating an aqueous dispersion of toner fines, ionic surfactant and nonionic surfactant, adding thereto a counterionic surfactant with a polarity opposite to that of said ionic surfactant, homogenizing and stirring said mixture, and heating to provide for coalescence of said toner fine particles.
In copending patent application U.S. Ser. No. 022,575 (D/92577), the disclosure of which is totally incorporated herein by reference there is disclosed a process for the preparation of toner compositions comprising
(i) preparing a pigment dispersion in a water, which dispersion is comprised of a pigment, an ionic surfactant and optionally a charge control agent; PA1 (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant and resin particles, thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent to form electrostatically bound toner size aggregates; and PA1 (iii) heating the statically bound aggregated particles above the resin Tg to form said toner composition comprised of polymeric resin, pigment and optionally a charge control agent. PA1 (i) preparing by emulsion polymerization a charged polymeric latex of submicron particle size; PA1 (ii) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an effective amount of cationic flocculant surfactant, and optionally a charge control agent; PA1 (iii) shearing the pigment dispersion (ii) with a polymeric latex (i) comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent to form a high viscosity gel in which solid particles are uniformly dispersed; PA1 (iv) stirring the above gel comprised of latex particles, and oppositely charged pigment particles for an effective period of time to form electrostatically bound relatively stable toner size aggregates with narrow particle size distribution; and PA1 (v) heating the electrostatically bound aggregated particles at a temperature above the resin glass transition temperature (Tg) thereby providing said toner composition comprised of resin, pigment and optionally a charge control agent. PA1 (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant in amounts of from about 0.5 to about 10 percent by weight of water, and an optional charge control agent; PA1 (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant and resin particles, thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent; PA1 (iii) stirring the resulting sheared viscous mixture of (ii) at from about 300 to about 1,000 revolutions per minute to form electrostatically bound substantially stable toner size aggregates with a narrow particle size distribution; PA1 (iv) reducing the stirring speed in (iii) to from about 100 to about 600 revolutions per minute and subsequently adding further anionic or nonionic surfactant in the range of from about 0.1 to about 10 percent by weight of water to control, prevent, or minimize further growth or enlargement of the particles in the coalescence step (iii); and PA1 (v) heating and coalescing from about 5.degree. to about 50.degree. C. above about the resin glass transition temperature, Tg, which resin Tg is from between about 45.degree. to about 90.degree. C. and preferably from between about 50 and about 80.degree. C., the statically bound aggregated particles to form said toner composition comprised of resin, pigment and optional charge control agent. PA1 (i) preparing a pigment dispersion in water, which dispersion is comprised of pigment, ionic surfactant, and optionally a charge control agent; PA1 (ii) shearing the pigment dispersion with a polymeric latex comprised of resin of submicron size, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent, and generating a uniform blend dispersion of solids of resin, pigment, and optional charge control agent in the water and surfactants; PA1 (iii) (a) continuously stirring and heating the above sheared blend to form electrostatically bound toner size aggregates; or PA1 (iii)(b) further shearing the above blend to form electrostatically bound well packed aggregates; or PA1 (iii) (c) continuously shearing the above blend, while heating to form aggregated flake-like particles; PA1 (iv) heating the above formed aggregated particles about above the Tg of the resin to provide coalesced particles of toner; and optionally PA1 (v) separating said toner particles from water and surfactants; and PA1 (vi) drying said toner particles. PA1 (i) preparing a pigment dispersion, which dispersion is comprised of a pigment, an ionic surfactant, and optionally a charge control agent; PA1 (ii) shearing said pigment dispersion with a latex or emulsion blend comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant; PA1 (iii) heating the above sheared blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates with a narrow particle size distribution; and PA1 (iv) heating said bound aggregates above about the Tg of the resin. PA1 (i) preparing a pigment dispersion in water, which dispersion is comprised of pigment, a counterionic surfactant with a charge polarity of opposite sign to the anionic surfactant of (ii) and optionally a charge control agent; PA1 (ii) shearing the pigment dispersion with a latex comprised of resin, anionic surfactant, nonionic surfactant, and water; and wherein the latex solids content, which solids are comprised of resin, is from about 50 weight percent to about 20 weight percent thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and optional charge control agent; diluting with water to form a dispersion of total solids of from about 30 weight percent to 1 weight percent, which total solids are comprised of resin, pigment and optional charge control agent contained in a mixture of said nonionic, anionic and cationic surfactants; PA1 (iii) heating the above sheared blend at a temperature of from about 5.degree. to about 25.degree. C. below about the glass transition temperature (Tg) of the resin while continuously stirring to form toner sized aggregates with a narrow size dispersity; and PA1 (iv) heating the electrostatically bound aggregated particles at a temperature of from about 5.degree. to about 50.degree. C. above about the Tg of the resin to provide a toner composition comprised of resin, pigment and optionally a charge control agent. PA1 (i) preparing a negatively or positively charged pigment dispersion in water, which dispersion is comprised of a pigment in an ionic surfactant; PA1 (ii) shearing at high speeds the pigment dispersion with a polymeric latex comprised of resin of submicron size in the range of from about 0.5 to about 1 micron, a counterionic surfactant with a charge polarity, positive or negative, of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby resulting in a uniform homogeneous blend of flocks with particles of less than or equal to from about 0.5 to about 1 micron in average volume diameter, and which particles are comprised of resin and pigment; PA1 (iii) heating the above sheared homogeneous blend below, from about 5.degree. C. to about 25.degree. C., the glass transition temperature (Tg) of the resin and wherein the Tg of the resin is in range of from about 40.degree. C. to about 85.degree. C. and preferably in range of from about 50.degree. C. to about 75.degree. C., while continuously stirring at from about 200 to about 1,000 revolutions per minute (rpm) and preferably from about 300 to about 700 revolutions per minute to form electrostatically bounded or attached toner size aggregates with a narrow particle size distribution; and PA1 (iv) heating at about 5.degree. C. to 50.degree. C. (at temperatures of 60.degree. C. to 105.degree. C.) the statically bound aggregated particles above about the Tg, which Tg is generally in range of 40.degree. C. to 85.degree. C. and preferably in range of 50.degree. C. to 75.degree. C., to provide coalesced particles of toner comprised of polymeric resin, pigment, and optionally a charge control agent; PA1 (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment of a diameter of from about 0.01 to about 1 micron, and an ionic surfactant; PA1 (ii) shearing at high speeds the pigment dispersion with preferably a positively charged latex blend comprised of resin of submicron size of from about 0.01 to about 1 micron, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent to form a uniform dispersion of solids of resin, pigment and optional charge additive in the water, and surfactant system of anionic/nonionic/cationic; PA1 (iii) heating the above sheared blend at a temperature of from about 5.degree. C. to about 25.degree. C. below the Tg of the resin, which resin Tg is generally in the range of 40.degree. C. to 80.degree. C. and preferably between 50.degree. C. to 75.degree. C., while continuously stirring to form electrostatically bound relatively stable (for Coulter Counter measurements) toner size aggregates with a narrow particle size distribution; PA1 (iv) heating the statically bound aggregated particles at a temperature of from about 5.degree. C. to about 50.degree. C. above the Tg of the resin, which resin Tg is generally in the range of 40.degree. C. to 80.degree. C. and preferably between 50.degree. C. to 75.degree. C., to provide a mechanically stable toner composition comprised of polymeric resin, pigment, and optionally a charge control agent; PA1 (v) separating the formed toner from the water blend by known means like filtration; and PA1 (vi) drying the toner; and PA1 (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment and an ionic surfactant; PA1 (ii) shearing at high speeds of about 3,000 to about 15,000 rpm the pigment dispersion with a latex blend comprised of resin particles, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant and a nonionic surfactant thereby causing a flocculation or heterocoagulation of the formed particles of pigment, and resin to form a uniform dispersion of solids in water and surfactants; PA1 (iii) heating the above sheared blend below about the glass transition temperature (Tg) of the resin particles while continuously stirring to form electrostatically bounded toner size aggregates with a narrow particle size distribution; and PA1 (iv) heating the statically bound aggregated particles above about the Tg, which Tg is in range of from about 40.degree. C. to about 80.degree. C. and preferably from 50.degree. C. to 75.degree. C., to provide a toner composition comprised of polymeric resin and pigment. PA1 (i) preparing a pigment dispersion in a water, which dispersion is comprised of a pigment, an ionic surfactant, and optionally a charge control agent; PA1 (ii) shearing at high speeds like 5,000 to 30,000 rpm the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, a nonionic surfactant and resin particles to achieve a homogeneous or uniform blend of flocks comprising resin particles, pigment particles, and optional charge control agent, water, and the above surfactant mixtures; PA1 (iii) stirring preferably at 500 rpm, and generally stirring in the range of from about 200 to about 1,000 rpm and preferably in the range of 300 to 700 rpm, for about 1 to 4 hours the homogenized mixture with optional heating at a temperature of from about 25.degree. C. to about 50.degree. C., but below (5.degree. C. to 25.degree. C.) the resin Tg (the resin Tg is preferably equal to 54.degree. C., and in the range between 45.degree. C. to 90.degree. C. and preferably between 50.degree. C. and about 80.degree. C.), thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin and charge control agent to form electrostatically bounded toner size aggregates; PA1 (iv) stabilizing said aggregates by addition of extra 0.5 to 10 percent of the total kettle volume of anionic or nonionic surfactant prior to heating above the resin Tg; and PA1 (v) heating to from about 60.degree. C. to about 95.degree. C. the statically bound aggregated particles above, for example 5.degree. C. to about 50.degree. C. above the resin Tg, which resin Tg (glass transition) is in the range of between about 50.degree. C. to about 80.degree. C. and preferably between about 50.degree. C. to about 75.degree. C., to form a toner composition comprised of polymeric resin, pigment, and optionally a charge control agent.
There are believed to be a number of process improvements of the present invention including, for example, the process equipment, namely the IKA SD41 (laboratory unit), IKA Dispax Reactor and the Megatrons, which continuously recirculate the pigment mixture with a latex mixture comprised of a polymer resin, anionic surfactant and nonionic surfactant thus ensuring that the mixture is evenly blended, homogeneous, or uniform as opposed to batch type of devices, for example a Brinkmann (PT/G35M) or IKA (G45M) polytron dispersing tools where the mixing or the blending occurs locally around the polytron dispersing tool resulting, especially at high viscosities, about 2,000 to 3,000 centipoise in a cottage cheese like blend. This behavior is further amplified and noticeable when (a) the solids content is increased from 11 percent to 15 percent in step (ii), and (b) the counterionic concentration to the ionic surfactant is increased from about 1:1 molar ratio to about 2:1 molar ratio for batch type of shearing devices.
In copending patent application U.S. Ser. No. 083,146 (D/93106), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner compositions with a volume median particle size of from about 1 to about 25 microns, which process comprises:
In copending patent application U.S. Ser. No. 083,157 (D/93107), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner compositions with controlled particle size comprising:
In copending patent application U.S. Ser. No. 082,741 (D/93108), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner compositions with controlled particle size and selected morphology comprising
In copending patent application U.S. Ser. No. 082,660 (D/93110), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner compositions comprising:
In copending patent application U.S. Ser. No. 083,116 (D/93111), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner compositions comprising